Booklets of the kind described above are usually manufactured in the following way:
A flat sheet of paper and/or plastic is folded such that it is divided into two cover sheets and a spine. A binding agent in the form of a bead of melt glue is attached to the inside of the spine by firstly heating and melting the glue to a semi-solid state and then cooling it, so that it will solidify and adhere to the spine. The cover sheets are then folded along the crease lines such as to form a cover, the bead of glue being oriented between the cover sheets. When the finished covers have been packed and distributed, the user will take a cover out of the package and insert a sheaf of paper in the cover, such that one side edge of the sheaf will bear against the bead of glue. He will then insert the cover containing the sheaf of paper into a binding machine, such that the outside of the spine will get into contact with a heating plate. After a certain amount of time, the glue will melt and the sheaf of paper will sink into it. The user will then remove the cover containing the sheaf of paper from the machine and the glue will be allowed to cool, the side edge of the sheaf of paper adhering to the spine so that a finished booklet is obtained.